The overall aims of the Clinical Core are to support other Cores and Projects and to initiate and facilitate clinical research related to sexually-transmitted diseases. The collaboration with the Behavioral Project is central to the support of other Cores and Projects. The Clinical Core will gather clinical and microbiologic data at baseline, 6 months, and 12 months on all patients enrolled in the Behavioral Project. The microbiologic data include the presence of T. vaginalis, herpes simplex, T. pallidum, N. gonorrhoea, C. trachomatis, human papillomavirus, genital mycoplasmas, bacterial vaginosis, and group B streptococcus. The Behavioral Core will identify 2,300 Mexican-American subjects distributed equally among pregnant patients without STDs, pregnant patients with STDs, non-pregnant patients without STDs, and non-pregnant patients with STDs. It is estimated that 30% of the 2,300 subjects will have one or more STDs. The Behavioral Project will collect demographic, behavioral and psychosocial data at similar intervals (0, 6 and 12 months). The combination of clinical, microbiological, psychosocial, behavioral and organism-specific virulence factors (as determined by the basic science projects) will increase the understanding of the configuration of factors responsible for STD transmission in a Mexican-American population. The cohort of patients defined by the Clinical/Behavioral researchers will provide data, subjects and organisms in support of other projects. Fresh isolates, complete with demographic, behavioral, and clinical data, will be supplied to the T. vaginalis Project, Herpes Simplex Project, and T. pallidum Project. Pregnant patients with documented STDs will be used as subjects in intervention and descriptive studies of the complications of pregnancy related to STDs. We will evaluate whether the treatment of T. vaginalis with metronidazole is effective in reducing preterm birth. Patients with HPV will be evaluated by Papanicolaou smear and colposcopy and the incidence of clinically apparent disease will be correlated with the phenotype of herpes simplex. The epidemiology and pathophysiology of herpesvirus 6 and Epstein-Barr virus will be explored in cohorts of pregnant and non-pregnant women in an effort to define the relationship of these organisms to other sexually-transmitted diseases. The Clinical Core will also evaluate the effect of operative laparoscopy on short- and long-term sequelae of acute pelvic inflammatory disease (PID). Hospitalized patients with PID will be randomized at initial laparoscopy to non-intervention or operative intervention. A second-look laparoscopy will be performed at 3 weeks. Patients will again be randomized between non- intervention and operative intervention. Patients will be followed for speed of recovery, pelvic pain, infertility and ectopic pregnancy. These patients will also be enrolled in the Behavioral Project to evaluate the effectiveness of educational intervention on recurrent STDs.